Children and adolescents suffering from juvenile rheumatoid arthritis or Crohn’s Disease got a dose of troubling news yesterday. The Food and Drug Administration announced a review of whether the drugs used to treat these conditions increase the risk of childhood cancer.

The blockbuster drugs under investigation (Enbrel, Remicade, Humira and Cimzia) are also used by adults, and the increased cancer risk for adult patients has been known for some time.

But the threat to patients under the age of 18 is only now been considered, after the accumulation of 30 reported cases of childhood cancer in the 10 years since the drugs went on the market.

The drugs block a molecule, called tumor necrosis factor or TNF, thereby switching off immune responses that make joints and tissues swell and redden. The drugs help calm overactive TNF in patients with certain types of arthritis, [the chronic bowel inflammation] Crohn’s disease, severe psoriasis, and other autoimmune diseases. But TNF is also part of the body’s defense against cancer.

On their labels, all of the drugs list cancer — particularly lymphoma, a cancer of white blood cells — among their serious possible side effects. The labels warn patients and their parents that the drugs lower the body’s ability to fight off infections [WebMD Health News].

The FDA said that about half of the reported cancers were lymphomas. The agency has asked four drug-makers to submit data about their products, and about any reported cases of young patients developing cancer while taking them. Recommendations are expected within six months.

The agency tried to tamp down alarm in its notice, advising patients that the agency “believes that the potential benefits of the use of TNF blockers outweigh the potential risks in certain children and young adults.” Some physicians agreed that the benefits of these drugs have been extraordinary.

Dr. Edward H. Giannini, professor of pediatric rheumatology at the University of Cincinnati, said that 70,000 to 100,000 children in the United States had juvenile idiopathic arthritis, and that the biotech drugs were “unequaled” in their ability to control the disease. “This was a disease that put kids in wheelchairs,” he said [The New York Times].

Image: National Institute of Arthritis and Musculoskeletal and Skin Diseases